Very commonly samples are taken of a patient's blood for laboratory tests. This blood is obtained from the patient's veins by means of a hypodermic needle inserted into a suitable superficial vein which has been previously distended by means of a tourniquet. The required quantity of blood is drawn into the syringe by pulling on the barrel of the instrument.
More recently the conventional syringe has been paritally replaced by a technique employing a series of preevacuated containers. When such a system is used, a single needle penetrates the vein and a series of evacuated containers are sequentially connected thereto for drawing a number of blood samples for different analyses. The individual containers are advantageous since they are disposable and presterilized and can secure consistent blood volume.
Such an arrangement can have problems, however, since the angle of vein penetration is sometimes awkward when the container is large. In some instances the puncture needle has been placed eccentrically on the container to minimize this problem. When the individual preevacuated containers are changed there is a significant chance that the puncture needle will be displaced or will penetrate the opposite wall of the vein. In either case this necessitates an additional puncture and often results in hematoma formation. The condition of the patient's vein and the skill of the operator are important factors in determining whether this may occur.
In addition, the preevacuated collection tubes often contain a substance such as anitcoagulant or blood preservative which can have significant adverse effects on the patient if it is aspirated into the patient's bloodstream. Such could happen, for example, if the container has developed a leak and the vacuum has been lost. This condition cannot be ascertained by simple inspection and careless work on the part of the person taking the sample could lead to undesirable toxic substances entering the patient's bloodstream.
Ordinarily when blood samples are taken, analysis is made on whole blood and on blood that has been centrifuged to yield plasma, serum, buffy layer and red cells in separate fractions. It is desirable to provide a technique for safely and quickly collecting blood from the patient, separating blood into the desired fractions, and possible initiating analysis within a closed system without exposure of the sample to the outer environnment. This serves to protect personnel from contamination and preserve the blood from external contamination.
Another diagnostic technique that is sometimes used, particularly for detection of respiratory diseases such as tuberculosis and cancer, is the collection and examination of sputum. The current collection technique has the patient cough and expectorate into a jar which is then sealed with a cardboard lid or screw on cap. In the laboratory the technician transfers the sample to suitable analysis devices. This technique is not only inefficient but is hazardous to the examiner. The hazard is compounded in the laboratory when the technician picks out portions of the sputum and smears it onto a glass slide or innoculates a bacteriological culture. Ordinarily this operation is carried on in an open environment or at best under an exhaust hood. In addition to the hazard to the technician, the operation is esthetically unpleasant because of the nature of the sample and consequently it is often rushed and poorly performed.
The detection of cancer cells in sputum offers the greatest potential for discovery in a curable stage. Unfortunately the technique is disappointly unsuccessful. A major impediment to the detection of cancer cells is the natural high viscosity of the sputum which prevents concentration of cellular elements by sedimentation or centrifuging. Attempts to employ a mucolytic substance have been thwarted by the fact that any such substance which will effect liquefaction of mucus generally also damages or destroys the cells that are sought.
The best technique has been to add 50% isopropyl alcohol to sputum and then mix in a common household blender. The blender must be cleansed thoroughly after each individual sputum sample which is very time consuming. In addition, the technique is carried out in an open system so that it is hazardous to laboratory personnel.
Another technique is to place the sputum on absorbent paper and pick out blood or purulent specks with forceps. Again, the hazards of this, as well as the unpleasant nature, are apparent and it is little wonder that cytotechnicians are not enthusiastic about preparation of sputum by any of the current methods.
It is, therefore, desirable to provide a sputum collection and sampling technique which can be accomplished with disposable elements and in a substantially closed environment which minimizes exposure of the sample to contamination and exposure of the technician to the sample.